79 
with the steel tape. The accuracy of the terrestrial measurements is characterized by the 
following values: 
Arithmetical mean of the mean planimetric errors of the control points, computed by 
means of intersections: -- 5,0 mm. 
Maximum mean planimetric error of the control points computed by means of inter- 
sections: = 17 mm. 
Arithmetical mean of the mean elevation errors of the control points, computed by 
means of intersections: 4,7 mm. . 
Maximum mean elevation error of the control points, computed by means of inter- 
sections: = 20 mm. 
Mean error of the directly measured distances, computed from their differences to 
the distances calculated from coordinates: == 15 mm. 
Maximum error of directly measured distances computed from their differences to 
the distances calculated from coordinates: == 55 mm. 
The points were signalized in different ways: 
a. by white pasteboard plates 40 X 40 cm in size; 
b. by white pasteboard plates 30 X 30 cm in size; 
c. by white pasteboard plates 20 X 20 cm in size; 
d. by whitewashing the surface of the bound-stones (monuments), 12 X 12 cm in 
size. 
Moreover, within a surface of 4 X 4 km around the experimental area itself the 
existing trigonometric points (spaced about 500 m) were signalized in order to obtain a 
sufficient number of signalized control points for the small-scale photographs. Out of a 
total of 17 different flights above the test area the Commission C selected 3 groups, with 
3 flight altitudes each, i.e. a total of 9 photographic flights (see table 1): 
Group I — RC5 Aviotar — flight altitude 1000 m, 1820 m, 2600 m. 
Group II — RC7 Aviotar — flight altitude 1020 m, 1850 m, 2650 m. 
Group III — RC7 Aviogon — flight altitude 960 m, 1400 m, 2150 m. 
Additionally one Centre has measured a second flight of Group I with the above 
mentioned flight altitudes. 
For plotting, the following material was forwarded to each Center: 
Glass diapositives and paper prints of the photographs, 
5 pass points in planimetry and elevation for each model, 
enlarged aerial photographs of the experimental area with indication of pass points 
and control points including point numbers and kind of signalizing. 
Moreover, nearly 80 non-signalized ground points and 45 non-signalized lines of the 
ground were especially indicated on the enlarged aerial photographs. They were surveyed 
by two different identificators of the “Eidgenôssische Vermessungsdirektion” by means 
of terrestrial methods. In connection with terrestrial surveying their photogrammetric 
plotting shall furnish a standard for the uncertainty in the definition of unsignalized 
points and lines on the terrestrial surface and shall offer a possibillity of giving infor- 
mations about the proportion of accuracy in terrestrial and photogrammetric identifi- 
cations of such objects. 
LW N= 
Apart from the coordinates and elevations of pass points all results of terrestrial 
surveying were bona fide deposited for the time being at the “Eidgenössische Vermes- 
sungsdirektion”. Only the coordinates and elevations of the pass points were communi- 
cated to the Centres. 
On April 8 and 9, 1954 the Commission C agreed upon the following plotting programme: 
1. The method of relative orientation is left to individual choice. 
2. In accordance with the procedure used in praxis the orientation of each stereoscopic 
pair pertaining to the same strip is to be effected alternately with internal and 
external base.